1. Field of the Invention
The present invention is related to a vehicle suspension assembly and more particularly to a multi-axis suspension system to independently control the vertical position and rotation of the axle housing relative to the frame.
2. Summary of the Prior Art
Suspension assemblies for vehicles are well known in the art. In conventional independent suspension systems, each side of an axle housing is independently free to move relative to the frame and with respect to the opposite axle shaft/housing. In such systems, a spring and shock absorber or strut assembly is used to allow dampened and biased displacement of the outer portion of the axle housing relative to the frame.
Another example of a vehicle suspension system attempts to account for travel over uneven surfaces. For example, it is known to rotatably connect an axle housing directly to the vehicle frame. In such assemblies, the position of the outer portion of the axle assembly relative to the frame may be controlled by hydraulically extendable cylinders or special linkage assemblies. Such systems, therefore, control the relative rotation of the axle housing directly to the frame. However, because, the axle housing is directly attached to the frame, the vertical distance of the axle housing may not be independently controlled.
An object of the present invention is to overcome and improve upon the drawbacks of the prior art suspension assemblies.
The present invention is directed to a multi-axis suspension assembly for vehicles. The assembly permits a rigid axle to freely rotate relative to the frame. The rigid axle is connected to a wishbone assembly which in turn is rotatably connected to the vehicle frame about a longitudinal axis of the vehicle. The axle housing is independently connected to the wishbone assembly and the relative vertical position of the axle assembly to the wishbone assembly is selectively controlled. A four bar linkage connects the axle housing to the wishbone assembly and defines the kinematic displacement of the axle housing relative thereto. A pair of extendable hydraulic cylinders forms a supplemental connection between the axle housing and the wishbone assembly. A position sensor senses the position of the axle assembly relative to the wishbone assembly. A control circuit controls the hydraulic cylinders in response to the sensed position of the axle housing. The vertical position of the axle housing relative to the wishbone assembly, and consequently relative to the vehicle frame, may be independently controlled apart from the rotation of the axle housing relative to the vehicle frame.